ASA 124th Meeting New Orleans 1992 October

3aAO1. Generation and dispersion of near-surface bubble densities.

Ming-Yang Su

Naval Res. Lab. Detachment, SSC, MS 39529-5004

John Cartmill

Planning Systems, Inc., Slidell, LA 70458

In four ocean experiments conducted in 1985, 1991, and 1992, extensive near-surface microbubble densities were obtained by both optical and acoustical techniques. The bubble radius (r) range for the former is 8--200 (mu)m and the range for the latter is 34--1200 (mu)m. Detailed analyses of the temporal variations (both on the order of 10 and 60 s) of these bubble densities reveal some common characteristics existing in all four sets of independent field measurements. Two maxima appear in the bubble density with the first one near r[sub 1]=100--150 (mu)m and the second one near r[sub 2]=20 (mu)m. The r[sub 1] peak occurs immediately when a fresh breaking wave plume is generated near the measuring sensor, while the r[sub 2] peak is more or less unchanged during the entire measurement period. These two peaks essentially divide the bubble density into two distinct radius ranges: the first range is 100